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POMVVM Light: how to send a parameter to ViewModel (when opening new window)?
 

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  1. POMVVM Light: how to send a parameter to ViewModel (when opening new window)?
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    <p>I am trying to learn MVVM with MVVM Light Toolkit in WPF. But I am stuck on one simple problem. </p> <p>I have an AddEditProfileWindow which basically has a textbox for profile name and a confirm button. It adds new profile to database table or updates name of existing profile. </p> <p>In MainWindow/MainViewModel I have a list of profiles and two buttons: "Add Profile" and "Edit Selected Profile". They both open this window via commands + messages. For example here is command for the "Add Profile" button</p> <pre><code> public RelayCommand OpenAddProfileWindowCommand { get { return _openAddProfileWindowCommand ?? (_openAddProfileWindowCommand = new RelayCommand( () =&gt; { Messenger.Default.Send(new NotificationMessage("OpenAddProfile")); })); } } </code></pre> <p>and it's receiver in MainWindow code behind</p> <pre><code>private void MessageReceived(NotificationMessage msg) { if (msg.Notification == "OpenAddProfile") { var window = new AddEditProfileWindow(); window.Owner = this; window.ShowDialog(); } } </code></pre> <p>So the problem is that I need to somehow pass a parameter to the AddEdit... Window/ViewModel (set IsEditing bool property in ViewModel for example) to change window behavior and customize it a bit (change title and the confirm button text to "Add" or "Update"). Also for updating I need Profile object (or at least Id) of selected record.</p> <p>For creating ViewModels I use ViewModelLocator and Unity</p> <pre><code> public ViewModelLocator() { var container = new UnityContainer(); ServiceLocator.SetLocatorProvider(() =&gt; new UnityServiceLocator(container)); container.RegisterType&lt;MainViewModel&gt;(new ContainerControlledLifetimeManager()); // singleton container.RegisterType&lt;AddEditProfileViewModel&gt;(); } public AddEditProfileViewModel AddEditProfile { get { return ServiceLocator.Current.GetInstance&lt;AddEditProfileViewModel&gt;(); } } </code></pre> <p>I have read a lot of similar threads and examples but still don't understand how should I pass parameters to view models. Some answers suggest creating view models on app startup (and make them singletons) in the ViewModelLocator and then I can send message before opening. But looks like not very clean and also I will need to reset view models before opening (via Cleanup() probably).</p> <p>Is there any better/easier/cleaner approach? </p>
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